Cooler



FIG. 1 is a top, front, left perspective view of a cooler showing our new design;

FIG. 2 is a front view thereof;

FIG. 3 is a left side view thereof; and,

FIG. 4 is a right side view thereof.

The broken lines showing the remainder of the cooler are for environmental purposes only and form no part of the claimed design. 

The ornamental design for a cooler, as shown and described. 